Gas operated arm prosthesis



Oc 28, 9 9 D. w. COLLINS GAS OPERATED ARM PROSTHESIS Filed June 9, 1967United States Patent 66 Int. Cl. A61f 1/06, N04

US. Cl. 3-1.2 3 Claims ABSTRACT OF THE DISCLOSURE An apparatus forflexing an arm prosthesis at the elbow comprising a cylinder aroundwhich is a slidable sleeve. Within the cylinder is a gas storage flaskwhich communicates, via valve means, with a space within the sleeve. Thesleeve is connected to a forearm member in such a manner that, when gasunder pressure from the flask is admitted to the space in the sleeve,the sleeve is moved slidably outwardly on the cylinder whereby the armmember is moved angularly about the elbow. The valve can be operated toshut off the gas pressure and opened to the atmosphere, therebypermitting the gas in the space to be exhausted, so that the forearm canreturn to its original position by virtue of its weight.

This invention relates to an arm prosthesis, and more particularly to adevice for flexing an arm prosthesis at the elbow. The arm prosthesismay be an artificial arm, or an articulated splint (known as a flailsplint) for supporting, and assisting movements of, a patient having anarm disability, for example a muscle or nerve disability causing partialparalysis.

It is an object of the invention to provide simple apparatus forproviding powered, or power-assisted, flexion of an arm prosthesis atthe elbow.

According to this invention apparatus for producing or assisting elbowflexion for an arm prosthesis comprises a cylinder, a sleeve slidablyand sealably fitting around the cylinder, a gas storage flask within thecylinder, a pneumatic connection between the flask and a space withinthe sleeve, and means connecting the sleeve to an arm member, thearrangement being such that when gas pressure is applied to the saidspace, the sleeve is moved slidably outwardly on the cylinder wherebythe arm memher is moved angularly about the elbow.

An example of the invention will now be described with reference to theaccompanying drawings, in which:

FIGURE 1 is a partial side elevation of an articulated arm asistingsplint or flail appliance, with parts of apparatus in accordance withthe invention shown in section; and

FIGURE 2 is a partial end elevation looking in the direction of arrow Aof FIGURE 1.

Referring to the drawings, a flail, appliance has an upper arm bar 15and a forearm bar 16 pivotally connected at an elbow joint 17, so thatthe bar 16 can be moved angularly with respect to the bar 15. A flexedposition of the bar 16 is indicated in dot and dash lines. Fixed to theupper end of the forearm bar 16 is a quadrant 13 having a peripheralgroove in which lies a wire 8, the wire being anchored to the groove atpoint 8A. The wire runs over a pulley 10 to a second anchor point 9. Thepulley is freely rotatable on axis 10A and is carried between the upperarm bar and a bracket 14.

It will be apparent that if point 9 is moved down, the wire will pull onthe quadrant at point 8A, and cause the lower arm bar 16 to moveangularly about the elbow.

ice

A str-ap 1D is fixed as shown to the bar 15. This strap encircles andholds a thickened part 10 of a cylinder IB having a closed lower end 1A.This cylinder 1A, IB, 1C is thus immovably fixed to the bar 15.

The internal size of the cylinder is such as to receive snugly the bodyof a gas storage flask 18 the end 18A of which projects from thecylinder as shown, and includes a gas inlet and exhaust valve 18B.

A sleeve 4 fits slidably over the outside of the cylinder. It is shownin its normal, upper position, abutting the thickened cylinder part IC.Extending down over the upper end of the sleeve 4 is a protective sleeve3 of plastics material.

The closed lower end 1A is grooved externally to seat two O-ring seals 5which engage the inner surface of the slidable sleeve 4. The sleeve 4has a closed lower end 6 with a bore 6A in which is fitted a gas inletnipple 7. Thus when a connection (not shown, but of well-known type)between the valve 18B and the nipple 7 and the valve 18B is opened, gasflows through the nipple 7 into -a space 4A between the lower ends 1Aand 6 respectively of the cylinder and sleeve 4, causing the sleeve toslide downwardly. The maximum stroke of the sleeve is indicated by thedot and dash line position shown, and in this position the top rim ofthe sleeve lies just above the lower rim of the protective sleeve 3.

Fixed to the lower end 6 of the sleeve 4 is a block 6B and fixed in turnto the block 6B is the anchor point 9 of the wire 8.

It will be seen that when pressure is admitted to the space 4A, theforearm bar 16 will be moved angularly. At the maximum outward stroke ofthe sleeve 4, the forearm bar 16 will be in the dotted line positionshown.

When the valve 18B is operated to turn ofl the gas pressure and isopened to the atmosphere, gas from the space 4A will be exhaustedthereby permitting the weight of the patients forearm, together withthat of the bar 16, to turn the quadrant in reverse direction, so thatthe sleeve 4 is returned to its nonnal, upper position shown in fulllines.

The quadrant, wire and pulley are housed between an inner metal plate 12(FIGURE 2) and an outer cover 13 of plastic material.

What I claim is:

1. Apparatus for producing or assisting elbow flexion for an armprosthesis comprising, a first and second arm member pivoted about anelbow joint, a cylinder, a sleeve slidably and sealably fitting aroundthe cylinder, said sleeve defining a space with said cylinder at one endthereof, a gas storage flask within the cylinder, a pneumatic connectionbetween the flask and said space within the sleeve, said connectionincluding means for selectively admitting and exhausting gas tosaid'space, and means connecting the sleeve to one of said arm membersand the cylinder to the other of said arm members, the arrangement beingsuch that when gas pressure is applied to the said space, the sleeve ismoved slidably outwardly on the cylinder whereby said one arm member ismoved angularly about the elbow joint.

2. Apparatus for producing or assisting elbow flexion for an armprosthesis comprising, an upper arm member and a forearm memberconnected for angular movement therewith, a cylinder fixed to said upperarm member, a sleeve slidably and sealably fitting around the cylinder,said sleeve defining a space with said cylinder at one end thereof, agas storage flask within the cylinder, a pneumatic connection betweenthe flask and said space within the sleeve, the connection includingvalve means whereby gas can be admitted to the space and exhaustedtherefrom, a quadrant fixed to the upper end of the forearm member, anda flexible pull element anchored at one 3 4 end to the quadrant andsecured at its other end to the 2,512,526 6/1950 Hauser 312.2 sleeve,the arrangement being such that when gas pres- 2,832,334 4/1958 Whitelaw128-25 sure is applied to the said space, via the said valve means,3,007,176 11/ 1961 Hafner 3-1.2 the sleeve is moved slidably outwardlyon the cylinder and exerts a pull on the element whereby the forearm 5FOREIGN PATENTS member is moved angularly with respect to the upper828,291 1/1952 Germany.

arm member; the gas on being exhausted from the space 117,204 GreatBritain. permitting the sleeve to return to its original position.

3. Apparatus according to claim 2, wherein the upper RICHARD GAUDET,Primary Examine! arm member mounts apulley over which the pull element10 L FRINKS Assistant Examiner passes.

References Cited US. Cl. X.R.

UNITED STATES PATENTS 3-12.3; 91-216; 128-25 2,259,911 10/1941 Tancredet al. 3-1.2 15

